function toggleThumbs(toggleControl, divToToggle)
{
  toggleControl.innerHTML = toggleControl.innerHTML == '«' ? '»' : '«';
  document.getElementById(divToToggle).style.display = document.getElementById(divToToggle).style.display == 'none' ? 'block' : 'none';

  new Ajax.Request('http://web.ccre.arq.up.pt/projectos/update_session.php', { asynchronous: true});
}